This application is based on and claims priority under 35 U.S.C. xc2xa7 119 with respect to Japanese Application No. 2000-281466 filed on Sep. 18, 2000, the entire content of which is incorporated herein by reference.
The present invention generally relates to movable covers on a vehicle. More particularly, the present invention pertains to an opening and closing control device for a cover, such as a sunroof panel or a power-window pane, provided at an opening of a vehicle.
Opening and closing control devices for controlling the movement of a cover provided at an opening of a vehicle in accordance with switch operation by an occupant of the vehicle are known. One example of such an opening and closing control device is disclosed in Japanese Patent Publication No. H05-25686. This document describes a sunroof opening and closing control device for controlling the slide opening/closing movement and tilt opening/closing movement of a sunroof panel. The sunroof panel is designed to perform the tilt open/close movement and the slide open/close movement in order by an electric motor and a drive unit. The sunroof panel is controlled to move in the tilt-open direction by rotating the electric motor in one direction from a completely closed position and is controlled to move in slide-open direction by rotating the electric motor in the reverse direction from a completely closed position.
In recent years, the opening and closing control device includes an entrapment prevention function which detects the entrapment of an occupant or an obstacle in the path of movement of a cover such as a sunroof panel and a power-window pane, and stops or reverses the open/close operation of the cover. Those opening and closing control devices require positional detection of the cover for controlling the open/close movement of the cover from the stopped condition or the condition moving in the reverse direction. In the aforementioned opening and closing control devices actuated by the electric motor, the position of the cover can be detected by detecting the rotational direction of the electric motor from a predetermined position and the rotational number to be calculated.
One method for positional detection of the cover involves detecting the position of the cover by calculating a pulse signal inputted from a Hall IC (i.e., a rotational number sensor) for detecting the rotation of a magnet disposed on the rotational shaft of the motor. In this method, the judgment of movement of the sunroof panel either in the open/close direction is performed referring to ON/OFF condition of a relay for controlling regular rotation, reverse rotation, and stopping of the motor. The calculation transaction of a positional counter is performed considering the stopping of the motor and the switching of the rotational direction.
However, with the foregoing method of positional detection judging the stopping of the motor and the timing of the reversion from ON/OFF condition of the relay, the motor is rotated by inertia for a while after the judgment of the motor stopping and the reversion. This rotation by inertia of the motor is not calculated on the positional counter. In addition, there is a possibility for a calculation error due to the possible counting of noise in the pulse signal.
Accordingly, a position detection switch for detecting the absolute position of the sunroof panel may be employed other than the sensor for generating the pulse signal such as the Hall IC in order to correct the calculated value (i.e., the position of the sunroof panel) of the positional counter based on a detection signal of the position detection switch. The sensor for positional correction such as the position detection switch is in most cases provided separate from the position of the motor and the control unit. Thus, a relatively long harness is required in addition to the position detection switch. Thus, known devices such as those discussed above suffer from drawbacks involving an increase in the size of the device, an increase in the number of components forming the device, relatively complicated control, and an increase in manufacturing cost due to the complex assembly procedure. These drawbacks lead to reduced manufacturing efficiency.
In light of the foregoing, a need exists for an opening and closing control device for a cover of an opening in a vehicle which is not as susceptible to the same drawbacks a discussed above.
A need also exists for an opening and closing control device which is able to detect the position of the cover with relatively high accuracy through use of a relatively simple construction, such as through use of a rotational sensor only.
According to one aspect of the invention, an opening and closing control device for a cover provided at an opening includes an electric motor for actuating the cover to open and close the opening, at least two rotational number sensors for generating pulse signals which have different phases from one another based on a rotational number of the electric motor, and a position detecting mechanism for detecting the position of the cover based on one of the pulse signals and for judging a moving direction of the cover in accordance with a signal level of one of the rotational number sensors when the other rotational number sensor detects an edge of the pulse signal.
With this construction, the rotational direction of the electric motor is judged by pulse signals having different phases which are generated by at least two rotational sensors. In this case, the edges of the signals from the past are not used for judgment. Instead, a signal level of one of rotational sensors which can be detected simultaneous with the edge of the other rotational sensor is used. Thus, the rotational direction can be judged immediately, even in the condition that reliable information cannot be obtained from the memory. Accordingly, the rotational direction can always be accurately judged and the error in the rotational number is not as likely to occur. This enables the positional detection of the cover with a relatively high degree of accuracy.
In accordance with another aspect of the invention, a opening and closing control device for a cover provided at an opening includes an electric motor which actuates the cover to open and close the opening, with the electric motor having a shaft on which is provided a magnet, and at least two rotational number sensors which generate pulse signals having offset phases based on rotation of the shaft and the magnet. The control device also includes a mechanism which determines the position of the cover based on one of the pulse signals and for judging a direction of rotation of the shaft based on a determination of a signal level of the pulse signal from one of the rotational number sensors when an edge of the pulse signal from the other rotational number sensor is detected.